The present invention relates generally to breathing devices, and will be specifically disclosed as a breathing tube and system capable of in vivo sterilization.
In many medical situations, the pulmonary functions (i.e., relating to the lungs) of a patient need to be monitored, controlled or accessed, and in many circumstances for days at a time. To achieve this, the medical field often uses a respiratory circuit which is connected to a ventilator, which is sometimes referred to as a respirator. Typically, respiratory circuits include a breathing tube (e.g., endotracheal tubes, tracheostomy tubes, laryngeal mask airways and the like) that acts as the interface between the patient and the respiratory circuit. For instance, an endotracheal tube is inserted through the mouth or nasal passage of the patient and into the trachea. Usually, a balloon or cuff surrounding the inserted end of the tube is inflated to provide a seal between the endotracheal tube and the trachea. Once sealed, the patient breathes through the endotracheal tube.
Once a breathing tube is connected to a patient, other components of the respiratory circuit are coupled to the breathing tube. Usually, a ventilator tube links the breathing tube with a ventilator which monitors, and if necessary can control, the pulmonary functions of the patient. Other components, such as junctions, moisture traps, filters, humidifiers and the like, optionally can be added to the respiratory circuit. For instance, drug delivery systems can be added to the respiratory circuit to deliver aerosolized medicine to the lungs of the patient. In some circumstances, medical caregivers require access to the lungs and/or trachea of the patient. For example, suction catheters are used to remove secretions in the patient""s lungs. In such circumstances, special junctions can be added to the respiratory circuit which allows such access without interrupting the monitoring or control of the pulmonary functions.
An ongoing challenge with respiratory circuits is maintaining a sterile environment. Indeed, one clinical study has concluded that xe2x80x9ctrying to maintain a sterile ventilator circuit for 24 hours is a difficult and perhaps impossible task.xe2x80x9d Contaminated Condensate and Mechanical Ventilator Circuits, Donald E. Craven, et al., Concise Clinical Study, p. 627. Due to the inherent moisture and warmth, respiratory circuits provide superb conditions for microbiological growth and colonization. Once colonization has started, the microbiological growth can easily spread to the patient, either airborne or through moisture condensation running down into the patient""s lungs, thus risking infections and complications, often resulting in pneumonia.
The problem of respiratory circuit colonization is especially prevalent within breathing tubes. For example, studies have documented the health risks from colonization in endotracheal tubes, sometimes referred to as a biofilm, which can be so extensive that the walls of the endotracheal tube become slimy and sticky. See Nosocomial Pulmonary Infection: Possible Etiologic Significance of Bacterial Adhesion to Endotracheal Tubes, Frank D. Sottile, et al., Critical Care Medicine, Vol. 14, No. 4, p. 265. Due to the close proximity to the patient""s lungs, any microbiological growth in the breathing tube can easily spread to the patient""s lungs. Condensed moisture can run down the breathing tube, over the biofilm and then to the patient""s lungs. Additionally, chunks of the biofilm can actually fall off the breathing tube and into the patient""s lungs.
Accordingly, an object of the invention is to provide a system for in vivo sterilization of a respiratory circuit. Additional objectives, advantages and novel features of the invention will be set forth in the description that follows and, in part, will become apparent to those skilled in the art upon examining or practicing the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
One aspect of the present invention is a system for in vivo sterilization of a breathing tube. A breathing tube has a proximal end, a distal end and an inner surface defining a lumen extending between the proximal and distal ends. The breathing tube is operative to define at least a portion of a respiratory circuit for a patient having a breathing cycle. A respirator is in fluid communication with the breathing tube and is capable of monitoring the breathing cycle of the patient. One or more ultraviolet light sources are in optical communication with at least a portion of the inner surface of the breathing tube. The light sources emit ultraviolet radiation for sterilizing the irradiated portion of the inner surface while connected to a patient. A synchronization mechanism is in communication with the respirator and is capable of controlling the ultraviolet light sources. The synchronization mechanism is operative to intermittingly activate the ultraviolet light sources relative to the breathing cycle.
Another aspect of the present invention is an apparatus for in vivo sterilization of a breathing tube. The breathing tube has a proximal end, a distal end and a lumen extending between the proximal and distal ends through which a patient can breathe. A respiratory circuit junction has two or more openings at least one of which is dimensioned to connect with the proximal end of the breathing tube. A detachable housing defines a cavity and is configured to enclose a substantial portion of the respiratory circuit junction when the respiratory circuit junction is connected to the breathing tube. The detachable housing is substantially opaque to ultraviolet radiation. A source of ultraviolet radiation is in the cavity of the detachable housing and is positioned so as to irradiate the lumen of the breathing tube and sterilize the lumen.
Still another aspect of the present invention is a method of in vivo sterilization of a breathing tube. A breathing tube has a flow passage through which a patient can breathe is connected to the patient. The breathing cycle of the patient is monitored. The breathing cycle has a plurality of inhalation portions, a plurality of exhalation portions, and a transitional period between exhalation and inhalation portions. One or more ultraviolet light sources are provided. A flow passage of the breathing tube is obstructed during a transitional period of the breathing cycle between an exhalation portion and an inhalation portion. At least one of the ultraviolet sources is activated while the flow passage is obstructed such that the ultraviolet radiation sterilizes the flow passage of the breathing tube and the obstruction in the flow passage prevents ultraviolet radiation from exiting the breathing tube. The ultraviolet radiation sources are then deactivated. The flow passage of the breathing tube is then unobstructed during the transitional period before the inhalation portion of the breathing cycles starts.
Yet another aspect of the present invention is a system for in vivo sterilization of at least a portion of a respiratory circuit. A breathing tube is connected to a patient. The breathing tube has inner surface defining a flow passage through which the patient can breathe. A ventilator tube is in fluid communication with the breathing tube and a ventilator. The ventilator tube has an inner surface defining a flow passage through which the patient can breathe. One or more ultraviolet radiation sources are positioned so as to irradiate at least a portion of the inner surface of the ventilator tube such that the irradiated portions of the inner surface are sterilized. A jacket surrounds a substantial portion of the ventilator tube and has an inner surface facing the ventilator tube. The jacket is opaque to ultraviolet radiation and is positioned relative to the ultraviolet radiation sources such that ultraviolet radiation emitted from the ultraviolet radiation sources is prevented from exiting the jacket.
Still other aspects of the present invention will become apparent to those skilled in the art from the following detailed description which is by way of illustration one of the best modes contemplated for carrying out the invention. As will be realized, the invention is capable of other different and obvious aspects, all without departing from the invention. Accordingly, the drawings and descriptions are illustrative in nature and not restrictive.